The present invention generally relates to a heating apparatus and more particularly, to a frame or cabinet construction for a microwave oven having a heating chamber, or for a so-called oven toaster or the like.
FIG. 5 shows a conventional frame construction 1 for a microwave oven, which mainly includes a front panel 2 having a generally rectangular shape, a rear plate 3 disposed at the back thereof, a bottom plate 4 fixed to lower edges of the front panel 2 and of the rear plate 3, a top plate 5 secured to upper portions of the front panel 2 and the rear plate 3 in a parallel relation with the bottom plate 4, and an oven structure 6 having a generally U-shaped cross section and fixed at its front and rear edges to the front panel 2 and to the rear plate 3, respectively, and at its upper edges to the top plate 5. Each of the plate members referred to above has folded portions as welding margins, at respective edge portions thereof to be connected with each other.
For assembling the conventional frame construction 1 in FIG. 5 as described above, the plate members 2,3,5 and 6 other than the above bottom plate 4 are preliminarily combined to each other through fixing by welding or the like, thereby forming an oven (i.e. a heating chamber) surrounded by the respective members. Thereafter, the plate members thus combined are subjected to a painting finish for subsequent drying. Then, the bottom plate 4 is fixed to the lower edges of the front panel 2 and the rear plate 3 by set screws 7, whereby the frame construction 1 for the microwave oven is completed.
However, since the known frame construction 1 is mainly constituted by the five plate members 2,3,4,5, and 6 as described above, press work, for example, in twenty-seven steps has been required for the manufacture of the plate members, and moreover, further processings have also been involved for welding such plate members to each other, and also for fixing the bottom plate 4 by the set screws 7 which must be supplied as separate parts.
Therefore, from the viewpoints of rationalization in processing steps, reduction in the number of required parts, improvement in the physical distribution, etc., it has been required to promote production efficiency.